This invention relates to improvements in earth moving equipment such as excavators and backhoes and, more particularly, to an improved thumb for use on such earth moving equipment.
Excavators are commonly used by contractors for various construction projects where large amounts of materials, earth and other items must be moved. Such excavators ordinarily have a boom, or arm-like structure extending from a main body of the excavator, a dipper stick pivotably attached to the boom, and a bucket. Typically the bucket is controlled via hydraulics mounted along the dipper stick.
It has been found to be desirable to add a thumb opposite the bucket to help facilitate grabbing objects. Use of thumbs can greatly decrease the amount of time required for a given project. Such thumbs have normally been elongate members fixed to the dipper stick which contact the bucket when the bucket rotates to a closed position. Some attempts have been made to make a thumb which is pivotable. One example is U.S. Pat. No. 5,813,822 to Pisco, which discloses a thumb with a common axis of rotation with the bucket and a second hydraulic system to move the thumb independent of rotation of the bucket. While such a design does increase the range of control of an operator, the addition of a second hydraulic line is relatively expensive. U.S. Pat. No. 4,932,832 to McCasland et al discloses a backhoe instead of an excavator with a bucket and a structure, which uses a single hydraulic line and is connected to an arm; via a complex series of linkages. Although this backhoe does avoid the use of a second hydraulic line, motion of the structure is not slaved to motion of the bucket, and the attendant complexity of the linkages makes it difficult to assemble and disassemble, restricts range of motion, and makes it difficult to move the structure out of the way when it is not needed.
It would be desirable to provide a control device for an earth moving equipment having both a pivotable bucket and a pivotable thumb which avoids the use of a second hydraulic line, is easy to assemble and disassemble, and which is of a low cost.
In accordance with a first aspect, a control device for earth moving equipment comprising a bucket pivotal about a bucket pivot between a closed position and an open position, a thumb pivotal about a thumb pivot between a first position and a second position, wherein the thumb pivot is separate from the bucket pivot, and a extension plate fixedly attached to the bucket and attached to the thumb pivot, wherein rotation of the bucket urges the thumb pivot to rotate around the bucket pivot and urges the thumb to move. In accordance with a second aspect, a retrofitting kit for retrofitting earth moving equipment so that the thumb is movable in response to movement of the bucket is also disclosed.
From the foregoing disclosure and the following more detailed description of various preferred embodiments it will be apparent to those skilled in the art that the present invention provides a significant advance in the technology and art of earth moving equipment. Particularly significant in this regard is the potential the invention affords for providing a high quality, low cost, control device increasing the ability to grab objects with the bucket and thumb. Additional features and advantages of various preferred embodiments will be better understood in view of the detailed description provided below.